If you're looking for an alfalfa nurse crop that provides higher-quality seeding-year forage than barley or oats, consider Italian ryegrass, says Paul Peterson, University of Minnesota forage specialist.
“It's got a lot of potential for the right situation, producing a very high-quality vegetative forage that remains vigorous and productive throughout late summer and into the fall,” he says.
In Minnesota field trials, Italian ryegrass produced two to three times the total dry matter yield of barley or oats, and its relative forage quality scores were nearly double those of oats.
The goal, says Peterson, is to use a high-enough seeding rate to get a good forage yield the first season, without smothering the alfalfa.
“The ideal seeding rate could vary anywhere from 2 to 10 lbs/acre, depending on your soil type and weather conditions,” he advises. “Lower rates are always safer, especially in heavier, cooler soils. If you've got sandier, drier soils, you can lean toward using a higher rate.”
Cutting frequency and height are also key management considerations with Italian ryegrass, he says.
“With our growing season length, we recommend four cuttings, the first about 50-60 days after emergence, and then about every 30 days after that. Good stands of winterhardy alfalfa varieties on fertile, well-drained soils can handle this intensive seeding-year harvest management.”
The fourth cutting in October is important because Italian ryegrass grows rapidly as temperatures cool.
“That's one of the key differences between Italian ryegrass and other annual ryegrass varieties, which tend to have more vigor early in the season and less in the fall,” says Peterson. “True annual ryegrasses also produce seed heads. But Italian ryegrass doesn't, which accounts, in part, for the latter's higher quality.”
Take early cuttings as close as you can to the ground, which helps slow the ryegrass regrowth and doesn't affect the alfalfa. “In our field plots, we cut the mixture fairly close, leaving just 2 or 3” of stubble, and it worked well.”
But don't plan on making dry hay from Italian ryegrass.
“It's really difficult to get it to dry enough to put up as hay,” he notes. “You're more likely to be able to make hay from annual ryegrass varieties, which are more stemmy and produce fluffier windrows that dry down better.”
Growers interested in trying Italian ryegrass as a nurse crop should plan to try a few seeding rates and keep the alfalfa seeding rate constant, he says.
“We've tried several seeding methods — using a grain drill or broadcasting the seed both work fine. We've even tried seeding the two crops in separate passes with the idea that it would give the alfalfa seedlings more room to grow and regrow against the more competitive Italian ryegrass.”
The grass responds well to starter fertilizer, especially because it doesn't typically emerge as quickly as oats, he adds. “It might also need more nitrogen in a starter fertilizer if you're planting on sandier soils.
“I encourage people to start small, maybe even plant just a few passes in the field to try it, using a few different seeding rates,” he says. “It will take some experimentation to get everything right in your specific field conditions, but I definitely think it's worth considering if you want higher-quality forage from your nurse crop.”